There are organizations that do not require a written exam and have certified individuals (past or present) based on their self-attestation. The ABFA believes individuals who want to perform forensic accounting services need to have formal forensic accounting education and training, including written examinations, to assess their core competencies.
It is increasingly commonplace for attorneys to ask expert witnesses if they had to take a written exam to receive their credential(s). We expect this question to be asked by more professionals in the foreseeable future.